Experimental detachments were made in Dutch rabbit eyes by injecting autologous serum or Hanks' solution into the subretinal space through a glass micropipette. The serum was resorbed at a rate of 0.064 +/- 0.023 microliter/mm2/hr, which is approximately half as fast as Hanks' solution. Both cyclic GMP and dibutyryl cyclic GMP accelerated serum resorption by 23%, whereas cyclic AMP and dibutyryl cyclic AMP (both used with IBMX) decreased the absorption rate by 46%. The absorption rate for Hanks' solution did not differ significantly between light and dark. Intravenous administration of acetazolamide (50 mg/Kg) and mannitol (2.5 g/kg) failed to alter the serum resorption rate significantly. Thus, cyclic nucleotides (and presumably metabolic transport) are important to absorption of serous fluid, but acetazolamide and hyperosmotic agents have less effect than on nonproteinaceous subretinal fluid.